Certain symptoms may predict fatal foodborne botulism

Aug 20, 2004 (CIDRAP News)  A distinctive group of symptomsshortness of breath, impaired gag reflex, and absence of diarrheamay be predictive of severe outcomes, including death, from foodborne botulism, a group of researchers reported recently.

The authors, from the Centers for Disease Control and Prevention and the National Center of Disease Control, Tbilisi, Republic of Georgia,collected data from the medical records of 706 patients hospitalized in the Republic of Georgia with botulism from 1980 through 2002. The country has the highest reported incidence of foodborne botulism in the world (0.9 cases per 100,000 population), according to the report.

Patients were considered to have botulism if this was listed as the final diagnosis. A trained epidemiologist completed a form about each patient that included patient demographic characteristics; medical history; history of present illness; physical examination findings at admission; clinical course, including complications, adverse reactions, and death; suspected source of disease; and results of laboratory tests.

The most common symptoms at admission were found to be fatigue (90%), muscle weakness (89%), and difficulty swallowing (81%). Ophthalmoplegia, ptosis, and slurred speech were the most common physical examination findings, present in 79%, 76%, and 58% of patients, respectively. Among the 705 patients for whom final outcome was known, 54 (8%) died. The group of symptoms classically considered to be predictive of botulismnausea and vomiting; dysphasia; diplopia; dry mouth; and fixed, dilated pupils, was present in only 2% of patients.

Classification and regression tree (CART) analysis was used to find clinical syndromes at presentation that were predictive of survival or death. In an analysis limited to patient age, signs, and symptoms, it was found that a history of shortness of breath or vomiting and normal facial muscle strength on physical examination at admission was 100% predictive of survival (odds ratio for death, 0%, P<.01). The clinical syndrome most predictive of death included shortness of breath, impaired gag reflex, and absence of diarrhea; patients who died were 22.6 times more likely to have this syndrome than were those who survived (95% confidence interval, 22-48).

Because botulism is among the diseases considered most likely for use as a bioterrorist weapon, any clues to outcome, such as those in this study, could be useful in triage in a mass-casualty setting. For example, in such an emergency situation, rapid transport to a facility providing higher-level care might be justifiably reserved for patients with the triad of symptoms identified as predictive of death.

The authors point out a number of limitations to their study and stress that validation outside of Georgia is needed.